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Weekend hikes gradually turn into strolls around the block. Joyful games of fetch or Frisbee are rare. Even standing up after a nap becomes a daunting task for your faithful friend.

Anyone who has had a lifelong canine companion has also had the difficult experience of watching that companion age, becoming increasingly stiff and less interested in play. The cause is usually osteoarthritis, which affects nearly one in every five dogs. The progressive, chronic degeneration of cartilage characteristic of this condition can occur in various joints and at almost any age, and the pain that results can be debilitating.

Geriatric pets most commonly develop it in the hip, stifle (knee) or elbow; however, it is also often seen in dogs with hip or elbow dysplasia as early as one to two years of age. Treatments range from supplements and antiinflammatory medications to surgical intervention and, increasingly, stem cell therapy.

Over the last decade, regenerative medicine, which has been around in the human sphere for nearly a quarter of a century, has become more common in veterinary medicine, and stem cell therapy is at the forefront. Stem cells are the body’s way of regenerating itself. Biological “blank slates,” they have the potential to specialize into one of many types of cells—skin, muscle, nerve, bone, tendon or ligament—and virtually any organ, and can be found in every organ in the body.

According to Dr. Samuel Franklin, assistant professor of small animal orthopedic surgery at the University of Georgia, a good candidate for the therapy “has failed treatment with less invasive and less expensive treatment and has arthritis that does not benefit from surgery.” Franklin also notes that while stem cell therapy helps modulate inflammation, “stem cells do not regenerate cartilage.”

In 2005, Dr. Brian Voynick of the American Animal Hospital in Randolph, N.J., was the first U.S. veterinarian to use stem cell therapy in dogs. He recommends it for young dogs with early signs of hip dysplasia and lameness because it is less invasive and more proactive than surgery.

“In cases of hip dysplasia, we see [improvement in] greater than 90 percent of cases—better mobility, less or no lameness, and increased quality of life. Sometimes, we see improvement on radiographs,” says Voynick. These results are typical when the therapy is used in conjunction with platelet rich plasma (PRP), a concentrated mix of platelets and growth factors taken from the patient’s own blood. According to Voynick, PRP turbocharges the cells’ activation. Once injected, stem cells have an anti-inflammatory effect within the joint and contribute to the reformation and architectural organization of the tissues.

Voynick recalls a case of a dog with severe hip osteoarthritis treated with stem cell therapy and PRP. “[Before treatment] she could not stand up from a lying position. Three days later, she was walking and wagging her tail.”

Normally, however, the response is not quite so dramatic. Though improvement in lameness and pain is sometimes seen within the first week, it more commonly comes within a period of about 90 days. The exact duration of the injection’s effectiveness is not known, but it is thought that, at least initially, monthly injections are most beneficial. Patients are rechecked at 30, 60 and 90 days post-treatment, and injections may be repeated if lameness returns.

Stem cell therapy is also being used for osteoarthritis resulting from cranial cruciate ligament (CCL) injuries. This common injury of the canine knee is more often seen in large-breed dogs but can affect dogs of all sizes. CCL injuries may be treated medically with rest and medication, or they may require surgery.

“With a full [CCL] tear, we want the stabilization of surgery,” says Voynick, adding that stem cell therapy can be beneficial post-operatively during rehabilitation, especially if the injury is accompanied by muscle loss.